1. Field of the Invention
The present invention relates to well casing perforation cleaning assemblies, and more particularly to a mechanical piercing array useful in opening clogged well perforations.
2. Description of the Prior Art
In my prior U.S. Pat. No. 4,892,145 issued Jan. 9, 1990, I have described a mechanical assembly in which an array of spring loaded blades is used to loosen debris collected in the perforations of a well casing. Since that time I have devised substantial structural simplifications, all having the object and purpose to render the assembly more reliable and convenient in use.
A well bore extending into a subsurface formation typically includes an internal liner formed as a stack of cylindrical casing segments. Such casing segments are either solid or perforated, depending on the strata in the formation from which the well fluids are drawn, thus serving as a selection mechanism for the fluids of interest to the well operator. As this well fluid is withdrawn formation fluids migrate towards the well bore, bringing with them particulate and dissolved matter which eventually collects in the casing perforations. Thus, the casing perforations must be periodically cleaned, with cleaning frequency greatly dependent on the characteristics of the formation.
Effective well cleaning entails both a wash sequence and the mechanical process directed at solid debris. Thus, the mechanical array is passed into the well bore in association with attachments that deliver cleaning fluid at pressure. The complexity of such a combination, along with the cost of personnel, the cost of the manipulative structure, and the remote locations of producing wells, all dictate a rugged mechanism that is easily worked and repaired in the field. It is one such mechanism that is described herein.